In general, DC power generated by a solar battery is converted to AC power by an inverter and supplied to a power system. The inverter converts the inputted DC power to AC power synchronized with the system voltage of the power system.
It is known to perform maximum power point tracking (MPPT) control on the inverter so as to maximize the power outputted from the solar battery. For instance, a solar power generation system is disclosed in which the MPPT control is performed at normal time to prevent distortion in the output current due to deficiency in the output voltage of the inverter (e.g., see Patent Literature 1).
The measurement accuracy in the quantity of electricity is important in confirming the operating condition of the inverter. However, the measurement methods known in the art are insufficient in accuracy.